Apparatus for cracking oil



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APPARATUS FOR CRACKING OIL Filed Dec. 25, 1936 3 Sheets-Sheet l I II II I' //V Tare c ONDENSEE F)? A c 7 0 IVA TING 70 WE R (3. E. KLEIBER APPARATUS FOR CRACKING OIL 3 Sheets-Sheet 2 Filed Dec.

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APPARATUS FOR CRACKING OIL Filed Dec. 23, 1936 3 Sheets-Sheet 5 FEED INLET "TIFF-IT U'Ufl' g K 5% 5a '42 $5 To W52 AER TING .DZZUM Patented June 25, 1940 UNITED STATES PATENT OFHQE APPARATUS FOR CRACKING OIL Carl E. Kleiber, Irvington, N. .lL, assignor to Standard Oil Development Company, a corporation of Delaware Application December 23, 1936, Serial No. 117,386 8 Claims. (01. 196-134) This invention relates to an apparatus for use medium under all conditions of operation and, in in cracking hydrocarbon oil and pertains more addition, to provide means for accurately conparticularly to an apparatus. for controlling the trolling the cleanliness of the reflux condensate, cleanliness of the intermediate condensate or the intercondensers are designed to produce more cycle stock obtained during the cracking treatcondensate than necessary for refluxing the top 5: ment, and which is normally subjected to further of the vapor separator under normal operating cracking treatment in the same or different conditions. cracking unit. In such equipment where the entire condensate In conventional cracking processes, it is a pracformed in the intercondensers is returned to the tice to secure an initial separation of the cracked vapor separating zone for control purposes the 101 products into vapors and residue upon leaving amount of condensate produced may be regulated the reaction zone and to then fractionate the by controlling the amount of cooling in the intervapors so separated to condense insufficiently condensers. However, this method of regulating cracked constituents as reflux condensate. This the amount of condensate returned to the vapor reflux condensate is then subjected to further separating zone is of limited-flexibility particucracking treatment in the same or different larly When the cooling medium, asin most equipcracking unit. In order to insure a maximum ment arrangements, is in the preheating circuit amount of cracking of this reflux condensate of the cracking unit. Because of such lack of during its passage through the reaction zone of flexibility it is difiicult with such an arrange 20.the cracking unit, it is essential that it be relament of equipment to effect a rapid and ac- 20., tively free of residual and coke-forming concurate control of the amount of refluxing to the stituents, for it is generally known that the temvaporizing zone so as toaccurately regulate the perature to which the charge may be heated and cleanliness and color of the condensate in the the amount of conversion to the desired products fractionating equipment.

which may be effected during the passage of the The usual practice in this type of cracking 25;.

oil through the cracking unit depends upon the equipment is to provide an excess of interconcleanliness of the charging stock passed thereto. denser surface and to combine the excess con- It has heretofore been a commonpractice to densate over and above that required to effect introduce a cooling oil into the top of the vapor the desired refluxing in the vapor separating zone separating zone in order to cool the cracked With the cycle condensate formed in the frac- 30.; vapors and condense and knock back heavy coketionating equipment and to subject it to further forming constituents and entrained residue concracking treatment therewith. Since, as already tained therein in order to effect the desired sepapointed out, the separation of heavy residual and ration of this residual cokeforming material coke-forming constituents from. the vapors is from the cracked vapors and thus insure a clean usually completed in the intercondensers, there 35-1,

condensate stock amenable to high temperature being difliculty in securing the desired separadrastic cracking conditions. tion in the vaporizing zone, it will be apparent The cooling fluid introduced into the top of that if aliquot portions of the total condensate the vapor separating zone as a cooling and refrom the intercondensers are returned to the fiuxing medium therefore, may be obtained from vapor separator and the remaining condensate a number of difierent sources. One practice is combined with the cycle stock from the fracto pass the vapors from the vapor and residue tionating equipment, the remaining condensate separating zone through heat exchange equipwill be contaminated with dirty constituents ment commonly referred to as reflux condensers which Will degrade the cycle stock.

or interconclensers positioned in the vapor line To avoid this, insofar as possible, it has been a leading from the vapor separator to the fractionpractice in some cases to separately withdraw ating equipment wherein the vapors are caused condensate formed in the separate passes oithe to undergo partial condensation and the condenintercondensers and return the dirtier condensates so formed are then returned to the vapor sate from the first passes to the vapor separator so separating zone as a refluxing medium. Accordand combine the relatively cleaner condensate 5 ing to this practice the separation of the dirty from the final passes of the intercondensers residual coke-forming constituents from the With the cycle stock formed in the fractionating vapors is eflected partly in the top of the vaporizequipment for further cracking. ing zone and partly in the intercondensers. In, In some instances, for example, a fixed amount order to provide the required amount of reflux of condensate from the initial passes of the 55 intercondensers, sufiicient to meet the minimum reflux requirements for the vapor separator is returned thereto and any additional condensate necessary to effect the desired cooling in the top of the vapor separating zone is obtained by returning an aliquot portion of the condensate from thefinal passes of the intercondensers. While this mode of operation offers some advantages over returning aliquot portions of the total eondensate, it is open to the objection that the aliquot portion of the condensate returned to the vapor separating zone as a reflux medium is or the same composition as that combined with the reflux condensate from the fractionating equipment, whereas under the most ideal conditions the cleanest condensate fraction would always be combined with the cycle condensate to be further cracked and the dirtiest fraction returned to the vapor separating zone as reflux control.

It has also been a practice in some instances, to provide sufficient valves and manifolding so that any one or more of the several condensates withdrawn from the separate passes of the intercondenser can be selectively passed either to the vapor separating zone or combined with the reflux condensate from the fractionating equip ment; While this makes it possible to combine the cleanest condensate with the reflux condensate formed in the fractionating equipment and return the dirtiest fraction to the vapor separating zone, it is open to the objection that it increases the burden on the operator to properly regulate the numerous manifold valves required, and it also materially increases the cost of equipment due to the relatively high cost of the regulating valves and manifolding so required.

One of the objects of my invention is to overcome the objections of the apparatus heretofore employed and provide a more simple and improved apparatus which will separate, collect and selectively distribute the separate condensate fractions removed from the separate passes of the intercondenser so that under all conditions of operation only the cleanest fraction will be combined with the reflux condensate formed in the fractionating equipment.

Another object of my invention is to provide a more simple and improved apparatus which may be operated by a single control so as to selectively distribute the condensate from the intercondensers to cause the dirtiest condensate to be returned to the vapor separating zone and the cleanest to the fractionating equipment.

A more specific object of my invention is to provide a simple gravity runback system for collecting and distributing condensate from the intercondensers which may be operated by a single control to cause any desired amount of the total condensate to be returned either to the vapor separating zone or combined with cycle stock and which under all conditions of operation will cause only the dirtiest condensate to pass to the vapor separating zone.

Other and more specific objects of my invention will be apparent from the more detailed description hereinafter, in which reference will be made to the accompanying drawings.

In the drawings:

Fig. 1 is a diagrammatic flow diagram of a simple oil cracking unit having my improved intercondenser and runback system connected therewith;

Fig. 2 is an enlarged detailed sectional view showing the construction of the intercondensers;

vapor and residue separating zone I5 with the fractionating tower 16.

As shown in Fig. 2, the fresh charging oil passes into a lower header El separated from the main body of the intercondenser l3 by means of a partition ES. The lower header l? communicates with an upper header l9 by means of a plurality of banks of tubes Ell. The lower header ii is divided into a plurality of vertical compartments by means of partition walls 2! and 22, and the upper header is divided into a plurality of staggered compartments by means of partition wall 23, so that the freshccharging oil is caused to pass alternately upwardly and downwardly through the intercondenser in indirect countercurrent heat exchange relation with the cracked vapors passing therethrough as hereinafter described.

The fresh charging oil after passing through the second intercondenser l3 passes through the first intercondenser l2 wherein it passes in further heat exchange relation with the vapors from the vapor separating zone 55. The intercondenser i2 is of the same construction as the intercondenser l3.

The fresh oil or cooling medium after passing through the first of the two intercondensers' emerges therefrom through line 24 which connects with a heating coil 25 located within the furnace 25. A by-pass line 24 may be provided around the intercondensers to regulate the amount cooling within the intercondensers and provide an additional range of flexibility permitted by the required heat-pickup by the cooling medium.

The oil during its passage through the heating coil 25 is heated to a cracking temperature and maintained at cracking temperature for a period suflicient to effect the desired cracking thereof. The cracked products from the heating coil 25 then pass through line 2'! to the vapor separating zone l5, wherein the vapors separate from the residue or fractions no longer suitable for further passage thru the immediate cracking zone. Residue separated in the vapor separating zone I5 is withdrawn therefrom through line 28 and passed to storage receptacles (not shown) or subjected to any desired further treatment.

The upper end of the vapor separating chamber l5 may be provided with suitable bafiies, such as disc and doughnut ballles to aid in knocking back residual constituents entrained in the vapors. Vapors separated in the vapor separating chamber [5 pass overhead through line M to the main body of the first intercondenser l2.

As shown in Fig. 2, the main body of the intercondenser is usually provided with one or more vertical bafiie plates 29, separating the intercondenser into a plurality of cooling zones through which the vapors pass alternately upward and downward in indirect countercurrent contact with the tubes 20 containing the fresh oil as a cooling medium.

The vapors during their passage through their several passes of the intercondenser are subjected to progressive cooling by the fresh oil and the higher boiling constituents thereof are condensed and separated from the vapors by collecting in the bottom of the main section of the intercondenser.

The separate passes of the intercondenser are provided with separate outlet ports and separate downwardly extending outlet pipes or legs 35, 3B, 3'! and 38 which connect with a common manifold line 3% so that condensate formed in each pass is separately withdrawn from the intercondenser and passes into the common manifold 39. It will be understood that the first condensate formed in the initial pass of the intercondenser will be the heaviest and dirtiest condensate and containing a maximum of coke forming residues while the condensate formed in the succeeding passes will be progressively lighter and cleaner.

The vapors after passing through the first intercondenser l2 and undergoing partial condensation therein continue through vapor line M to the second intercondenser l3, wherein they are subjected to further partial condensation. As

" already described, the second intercondenser I3 is of the same construction as the firstintercondenser. The condensates formed in the separate passes of the second intercondenser l3 are withdrawn through lines 4!, 42, 43 and M, which also connect with the main manifold line 39.

Vapors remaining uncondensed after passing through the second intercondenser l3 continue through line M to the fractionating tower H3 wherein they are subjected to fractionation to condense insufficiently cracked constituents as reflux condensate. Vapors remaining uncondensed in the fractionating tower l6 pass overhead through line 45 to a condenser 46 wherein the desired distillate is condensed. Products from the condenser 46 then pass to a distillate receiver 41, wherein fixed gases separate from the distillate. The desired distillate product is withdrawn from the receiver 41 through line 48 and the fixed gases pass overhead through line 49 provided with a valve 50 for maintaining the de sired pressure on the system. As a means of controlling the fractionation operation performed in tower IS a part of the cooled distillate withdrawn from receiver 41 may be returned to the top of tower l6.

Reflux condensate formed in the fractionating tower I6 is withdrawn from the bottom thereof through line 5! and is forced by means of pump 52 to the inlet side of the heating coil 25 where it combines with fresh makeup oil for the process. While I have shown the recycling of the reflux condensate'to the original cracking coil, it will be understood that in many types of operations this reflux condensate is subjected to separate cracking treatment under optimum conditions for converting or cracking this type of stock.

As already pointedout in the objects of my invention, I provide a simple gravity runback system for the condensate formed in the intercondensers, which makes possible the separation of the total condensate into a relatively clean fraction and a relatively dirty fraction by the operationof a single control valve. In practical operations, the relatively clean fraction is combined with the cycle stock formed by condensing insuificiently cracked constituents of the vapors. To this end, the clean fraction may be introduced directly into the fractionating tower H5 or it may be combined with the cycle stock formed therein, in a separate storage. receptacle, not shown.

let line 14.

Likewise, in practical operations, the dirtiest fraction of the intercondenser condensate is returned to the top of the vapor separator as a reflux medium therefor, although this stock may be withdrawn from the system and utilized in other manners,and a separate reflux medium introduced into the top of the vapor separator.

Referring particularly to the modification shown in Figs. 1 and 3, the manifold 38 receiving condensate from the intercondensers connects at the end nearest the second intercondenser with a line 53, provided with a throttle valve 54. Line 53 connects with the fractionating tower it through line 55, so as to discharge condensate from line 53 directly into the fractionating tower. A branch line 56 is also shown for withdrawing any desired part or all the condensate from line 53 from the system.

The opposite end of the manifold 39 nearest the vapor separator l5 connects with an upwardly extending inverted U-shaped pipe line 51, having the apex communicating with a vent line 53. Vent line 58 connects with the vapor line It beyond the second intercondenser H5.

The vertical height of the inverted U-shaped pipe line 5i determines the level of liquid maintained in the runback system. This height should be sufficient to maintain the manifold 39 completely filled with liquid throughout the full length thereof, but should not be high enough to cause condensate from the final pass of the intercondenser 13 to overflow into the vapor out- As a matter of practice, it is preferred to terminate the upwardly extending U- shaped section 51 below the condensate outlet ports from the intercondensers so as to maintain the liquid level within the legs 43 and id, connecting the manifold 39 with the final passes of the second intercondenser It, rather than in the main shell of the latter intercondenser.

The level of liquid condensate in the individual legs 35, 35, 3'! and 3B for the first intercondenser l2, and M, 32, 43 and M! for the second intercondenser l3, will depend upon the vapor pressure above the liquid in the respective legs and the level of liquid in the individual legs will be progressively higher from left to right as shown in Figs. 2 and 3, due to the drop in pressure of the vapors during their passage through the intercondensers. These legs should be of sufiicient length therefore to insure a liquid seal at the point of junction of the first leg 35 with the manifold 35!, in order to prevent vapors from entering the manifold 39 by-passing the various passes of the intercondensers and inducing an unsatisfactory operation of the equipment. In this connection, it is worthy of note that it is of extreme importance to my invention to maintain the manifold line 39 completely filledwith liquid, for the presence of vapors therein causes agitation of the condensate from the various legs and the surging of the condensate back and forth through the manifold and making it impossible to effect a sharp separation of condensates from the separate condensate legs.

The line 53 communicating with the manifold 39 at the end adjacent the second intercondenser i3 is provided with a vent line 59 which also communicates with the vapor line M beyond the second intercondenser. As a matter of practice, it is usually found desirable to merge the vent line 58 and the vent line 59 to the same point in the vapor line M, so that both ends of the manifold 39 will be under substantially the same back pressure, except for the difference in pressure drop through the vent lines themselves. The vent lines 58 and 59 permit vapors formed by commingling relatively colder condensate formed in the later vapor passes of intercondensers with the relatively hotter condensate formed in the earlier passes of the intercondensers to rapidly separate from the two streams of the combined condensate at both ends of manifold 39. It has been found, for example, that unless vent lines of this character are provided of sufficient size to rapidly remove the vapors formed in the manifold 39, there will be a constant surging of condensate in the manifold with a corresponding change in the level of condensate in the Vertical legs 35, 36, 31, 33 and il, 42, 33 and M. This change in level will in turn change the pressure on the liquid passing through the control valve 5? and the surging of the condensate back and forth longitudinally in the manifold of 39 will cause contamination of condensate formed in the final passes of the intercondensers with condensate formed in the initial passes and thus destroy one of the important objects of my invention.

The upwardly extending inverted U-shaped pipe section 51 connecting with the manifold line 33 connects with a downwardly extending U shaped section 68 which terminates within the vapor separator 55 at a point substantially below the condensate liquid levels in the runback legs 35, 36,- 37, 39, etc. A separate withdrawal line 5! is provided whereby a part or all of the condensate flowing to the Vapor separator may be diverted from the process.

By the construction described above, it is possible, in accordance with my invention, to maintain a constant level of liquid in the run'back system extending from the apex of the inverted U-shaped section 5'! to the throttle valve 54 so that for any given setting of the valve 5% a uniform flow of condensate therethrough will be attained, while the surplus condensate will be automatically diverted in the opposite direction. As already pointed out, by providing means to insure that manifold line 39 is completely filled with liquid, by preventing any portion of the vapors from the intercondenser passing into the manifold and by effecting a rapid separation of vapors formed in the manifold, surging and agitation of the condensate within the manifold is avoided so that any desired portion of the relatively dirtiest condensate from the earlier passes of the intercondenserswill be caused to flow toward the vapor separator and the remaining relatively cleaner condensate caused to flow toward the fractionating tower.

For example, if it is determined by inspection of condensate samples from the various legs of the intercondensers that only the condensate collected in the last two legs 43 and 4 3- is sufficiently clean for use as cracking stock, the throttle valve 54 will be set to withdraw condensate at the same rate it collects in these two legs. That portion of the manifold between legs 42 and 43 Will then become a zone of quiescence and the condensate collected in the first six legs of the intercondensers will pass toward the vapor separator and the condensate formed in the, last two legs will flow toward the fractionating tower.

The modification shown in Figs. 1 and 3, wherein the control valve is located in the line connecting the manifold 39 with the fractionating tower It, finds. particular advantage in processes Where it is desired to accurately control the cleanliness of the condensate subjected to recracking. In other processes, it is often desirable to regulate the amount of reflux medium introduced into the vapor separator so that the tar withdrawn as residue through line 28 is of a desired quality in such respects as gravity, etc. Figure 4 shows a modification of my invention wherein the amount of reflux return to the separator I5 is subjected to primary control and the surplus condensate formed in the final passes of the intercondensers is diverted to the fractionating tower it. According to this modification the line 53 leading from the manifold 39 to the fractionating tower i6 is provided with an inverted U-shaped section 52 similar to that shown in line 5'! of Fig. 1 which serves to maintain the manifold 39 completely filled with liquid. As shown the line connecting the manifold with the separator is provided with a variable speed pump 63 which serves as a control for regulating the amount of reflux required for the separator. The excess condensate passes in the opposite direction through line 53 to the fractionating tower H5 or out of the system through line 56. In lieu of the variable speed pump 63 a simple throttle valve 54 such as that located in line 53 in Fig. 1 may be employed. The control valve is preferred rather than the variable speed pump and the latter is used only when previous designs do not provide sufficient gravity head to permit'return of condensate to the separator.

In other respects the apparatus is the same as that shown in Figures 1 to 3.

While I have shown two separate intercondensers l2 and I3, it will be understood that my invention is not limited thereto. A single intercondenser of desired capacity or three or more intercondensers may be substituted therefor. Also in lieu of using fresh charging stock as a cooling medium in the intercondensers, other cooling mediums may be employed. Moreover, the cooling medium may be passed in parallel through the separate intercondensers rather than in series. However, to obtain the greatest benefits from my invention the vapor passing through the intercondensers should contact with progressively cooler heat exchange surface so that the condensates withdrawn from the successive legs will be of progressively increasing cleanliness.

Having described the preferred embodiment, it is understood that my invention is not limited thereto but includes such other variations and modifications as come within the spirit and scope thereof.

I claim:

1. In an oil cracking apparatus, means for separating the cracked products into vapors and residue, a vapor line, intercondenser means disposed in said vapor line for fractionally condensing the cracked vapors into a plurality of condensate fractions of different boiling range, a fractionating column means for separately removing said condensate fractions from said fractionating means, a common manifold conduit means for introducing said condensate fractions so removed into the common manifold conduit at spaced points longitudinally thereof in the order of the relative boiling range of said fractions, whereby the lowest boiling condensate is introduced into said manifold conduit adjacent one end thereof and the highest boiling condensate fraction is introduced into said manifold conduit adjacent the opposite end thereof, a vent pipe in communication at one end thereof with the manifold at the end thereof where the highest boiling fractions are received and at the other end with the vapor line and a second vent pipe in communication at one endthereof with the manifold conduit at the end where the lowest boiling fractions are received and at the other end with the vapor line, for, maintaining the condensate in said manifold conduit under substantially uniform pressure, means for Withdrawing condensate from each end of said manifold conduit and means operated by a single control for regulating the relative amount of condensate withdrawn from each end of said mania fold.

2. In an oil cracking apparatus a vapor sepa: rator for separating the cracked products into vapors and residue, a fractionating column for fractionally condensing insufficiently cracked constituents of said vapors, a vapor conduit connecting said vapor separator with said fractionating column, an intercondenser positioned in said vapor conduit for condensing higher boiling constituents of said vapors, means dividing the intercondenser into a plurality of separate cooling zones of progressively lower temperature, means for separately removing condensate formed in each of said cooling zones, a common manifold, means for introducing the condensate withdrawn from each of said cooling zones into the common manifold conduit at spaced points longitudinally thereof in the order of the relative boiling range of said condensates, whereby the lower boiling condensate is introduced intosaid manifold conduit at one end thereof and the highest boiling condensate is introduced at the opposite end thereof, outlet pipes connected at each end of said manifold conduit for withdrawing condensate therefrom, a control valve in only one of said outlet pipes, a vent pipe in communication at one end thereof with the manifold at the end thereof where the highest boiling fractions are received and at the other endwith the vapor line and a second vent pipe in communication at one end thereof with the manifold conduit at the end where the lowest boiling fractions are received and at the other end with the vapor line, for maintaining the condensate within said manifold to substantially uniform pressure, whereby condensate is caused to discharge through said control valve at auniform rate for each setting thereof and surplus condensate is caused to discharge to the other of said outlet pipes.

3. In an oil cracking apparatus, a vapor separator adapted to separate the cracked products into vapors and residue, a fractionating column, a vapor conduit connecting said vapor separator with said fractionating column, an intercondenser positioned in said vapor line adapted to condense higher boiling constituents from said vapors, means for separating said intercondenser into a plurality of cooling zones, whereby the vapors passing therethrough are subjected to progressive cooling actionto form a plurality of condensate fractions, means for separately removing said separate condensate fractions from said cooling zones, a manifold con-i duit, means for introducing the condensate fractions into said manifold conduit at spaced points longitudinally thereof in the order of the relative boiling points of said condensates, whereby the lowest boiling condensate fraction is introduced into said manifold adjacent one end thereof and progressively higher boiling constituents are introduced into said manifold conduit at successive points longitudinally thereof, an outlet pipe connected to each end of said manifold conduit, a control valve in one of said outlet pipes, vent pipes in communication with opposite ends of the manifold conduit and the vapor conduit positioned in the other of said outlet pipes for maintaining a constant pressure on the condensate in said manifold conduit, whereby for any given setting of the control valve condensate will be discharged ,therethrough at a uniform rate, and means for automatically discharging any surplus condensate formed in said intercondenser through the other of said outlet pipes.

4. An oil cracking apparatus, with a vapor separator adapted to separate the cracked products into vapors and residue, a fractionating column for condensing insufficiently cracked vapors, a vapor conduit connecting said vapor separator with said fractionating column, an intercondenser positioned in said vapor conduit adapted to progressively cool said vapors over an extended temperature range, means dividing said intercondenser into a plurality of cooling zones adapted to condense fractions of different boiling range, outlet pipes communicating with each of said cooling zones for separately removing condensate formed therein, a common manifold conduit connecting each of said outlet pipes for receiving condensate from each of said cooling zones, means forfintroducing the condensate into said common manifold at spaced points longitudinally thereof in the order of the boiling range of said condensate, outlet pipes at each end of said manifold conduit for removing condensate therefrom and control valve in one of said outlet pipes, whereby for any given setting of said control valve condensate is discharged therethrough at a uniform rate and any surplus condensate formed in said intercondenser is discharged through the other of said outlet pipes and means comprising vent pipes in communication with opposite ends of the manifold cone duit and the vapor conduit at a point between the intercondenser and the fractionating column for removing vapors formed in said manifold conduit by comrningling of hotter and colder condensate fractions to prevent agitation of said condensate within said manifold whereby the condensate withdrawn from one end of said manifold has a higher boiling range than the condensate withdrawn from the opposite end of said manifold.

5. In an oil cracking apparatus, a vapor separator adapted to separate the cracked products into vapors and residue, a fractionating column adapted to fractionally condense insufficiently cracked constituents of said cracked vapors, a vapor line connecting said vapor separator with said fractionating column, an intercondenser positioned in said vapor line adapted to progressively cool said vapors over an extended range, means separating said intercondenser into a p1urality of cooling zones of progressively lower temperature, downwardly extending outlet pipes connected to each of said coolingzones adapted to withdraw condensate formed therein, a horizontal manifold conduit connecting each of said downwardly extendingoutlet pipes for receiving condensate from each of said cooling zones at spaced points longitudinally of said conduit in the order of the boiling range of said condensate fractions, an outlet pipe at each end of said horizontal manifold conduit for withdrawing con densate therefrom, a control valve in one end of said outlet pipes, an upwardly extending inverted U-shaped section communicating with the manifold at successive points other of said outlet pipes adapted to maintain a liquid seal and provide a constant level of liquid in said manifold and downwardly extending outlet pipes, a vent pipe connecting the U-shaped section with the vapor line and a second vent pipe connecting the end of the manifold conduit which is in communication with the outlet pipe carrying the control valve and the vapor line for removing vapors formed in said manifold conduit by commingling of separate condensates introduced therein and to prevent agitation of condensate within said manifold conduit.

6. In an oil cracking. apparatus, a vapor :separator for separating the cracked products into vapors and residue, a fractionating column adapted to fractionally condense insufliciently cracked constituents as reflux condensate, a vapor conduit connecting said vapor separator with said fractionating column,an intercondenser positioned in said vapor conduit adapted to progressively cool said vapors over an extended temperature range, means for dividing said intercondenser into a plurality of cooling zones of progressively lower temperature, a downwardly extending outlet pipe communicating with each of said cooling zones for separately removing condensate formed therein, a horizontal manifold conduit connecting each of said downwardly extending pipes for receiving the separate condensate fractions formed in said separate cooling zones at spaced points longitudinally of said manifold conduit in the orderof the boiling range of said condensates, whereby the lowest boiling condensate is introduced into said manifold at one end thereof and progressively higher boiling condensate fractions are introduced into said longitudinally thereof, a tubular conduit connecting the end of said manifold receiving the highest boiling condensate with said vapor separator, a tubular conduit communicating with the opposite end of said manifold for withdrawing lower boiling condensate, an upwardly extending inverted U- shaped section in one of said tubular conduits communicating with the ends of said manifold of a height sufiicient to maintain a constant level of liquid in said manifold and downwardly extending outlet pipes, vent pipes at each end of said manifold connected to the said vapor conduit for removing vapors formed therein by the commingling of different condensates introduced into said manifold, and a control valve positioned in the tubular conduit communicating, with said manifold at the end opposite the one having the inverted U-shaped section.

'7. In an oil cracking apparatus a vapor separator adapted to separate the cracked products into vapors and residue, a fractionating column for fractionally condensing insufficiently cracked constituents, a vapor conduit connecting said vapor separator with said fractionating column, an intercondenser positioned in said vapor conduit adapted to progressively cool said vapors over an extended range, a plurality of vertical baffies positioned in said intercondenser dividing the same into a plurality of cooling zones, means causing said vapors to pass around said baffles in an alternate upward and downward direction,

downwardly extending outlet pipes communicating with the bottom of each of said cooling zones to separately remove condensate formed therein of progressively lower boiling range, a common manifold connecting said downwardly extending outlet pipes to receive separate condensate removed from said cooling zones, a tubular conduit connecting the end of said manifold conduit receiving the highest boiling condensate with the vapor separator, an upwardly extending inverted U-shaped section formed in said last-named conduit to provide a liquid seal of suiiicient height to maintain said manifold completely filled with condensate throughout the full length thereof, a vent line connecting the upper end of said inverted U-shaped section with the vapor conduit beyond said intercondenser, an outlet conduit communicating with the other end of said manifold receiving the lowest boiling condensate fraction, a vent line connecting said last-named outlet conduit with the vapor conduit beyond said intercondenser and a control valve positioned in said last-named outlet conduit whereby regulated amounts of lower boiling condensate are withdrawn therefrom and the remaining condensate formed in said intercondenser is passed to said vapor separator.

8. In an oil cracking apparatus, a vapor separator adapted to separate the cracked products into vapors and residue, a fractionating column adapted to condense insufficiently cracked constituents, a vapor conduit connecting said vapor separator with said fractionating column, an intercondenser positioned in said vapor conduit adapted to progressively cool said vapors over an extended temperature range, a plurality of baiiles positioned in said intercondenser to cause said vapors to pass therethrough in an alternate up ward and downward direction through a plurality of cooling zones of progressively lower temperature, downwardly extending outlet pipes communicating with the bottom of each of said cooling zones for separately removing condensate fractions of progressively lower boiling range from said cooling zones, a manifold conduit communicating with said downwardly extending pipes to receive the condensate discharged therethrough, said condensate fractions being introduced into said manifold at successive points in the order of their boiling ranges, a tubular conduit connecting the end of said manifold receiving the highest boiling condensate with the vapor separator to return condensate formed in said intercondenser to said vapor separator as a reflux medium therefor, control means positioned in said conduit for regulating the amount of condensate returned to said vapor separator, an outlet conduit connected to the opposite end of said manifold receiving the lowest boiling condensate from said intercondenser, means in said lastnamed outlet conduit for maintaining a constant level of liquid in said manifold and said downwardly extending outlet pipes and vent lines positioned at the ends of said manifold and connected to the vapor line for removing vapors formed in said'manifold by the commingling of separate condensates introduced therein.

CARL E. KLEIBER. 

